Realtime Blackhole Lists (RBLs) Anti-Spam Policies MailSite's anti-spam policies allow you to block mail from specific hosts or users, and include the following options: Block mail from blacklisted hosts. Sources of high-volume spam are tracked by blacklist services, which provide lists of sites that have been responsible for such mailings. MailSite allows you to block all messages from hosts named by a blacklist service, and also allows you to select the blacklist service you wish to use. The default service is the MAPS Realtime Blackhole List (RBL). Use of this feature is recommended for ISP sites. Below is a brief list of RBL server which may be available be free of charge:

• www.orbl.org
• www.spamcop.net
• relays.osirusoft.com
• dsbl.org
• ordb.org

Additional Notes:

• Rockliffe is not associated with the listed RBL sites in any way and cannot provide any support, guarantees, or recommendations on the use of these sites.
• Performance may vary when using these sites depending on their bandwidth and their current volume of Internet traffic.
• The more RBL sites you use, the longer processing time may be needed by MailSite to process these request which may effect performance.
• If you select a RBL site the requires a subscription fee and you do not have one, a definite performance issue will arise.

References & Resources:
MailSite Administration Guide (Security - SMTP Security Sections)